CONSTRUCTION OF COMPONENT MAPS FROM AEROMAGNETIC TOTAL FIELD ANOMALY MAPS¹

Abstract

PEDERSEN, L.B., RASMUSSEN, T.M. and DYRELIUS, D. 1990. Construction of component maps from aeromagnetic total field anomaly maps. Geophysical Prospecting 38,795-804.Total field anomalies as defined from normal aeromagnetic surveys give good approximations of the anomalous components along the direction of the main geomagnetic field, which is generally much larger than the anomalous field. Using the relations between vertical and horizontal components of the field, the total field anomaly is related to any vertical or horizontal component and the corresponding horizontal and vertical derivatives. An example from the Siljan impact structure indicates that such directional filters may be applied to extract useful information from magnetic maps.

A framework for 3-D joint inversion of MT, gravity and seismic refraction data

“…In addition to the first spatial derivative of the gravitational potential it is also possible to measure the elements of the second spatial derivatives that form the so‐called full gravity tensor Γ (FTG) (Li & Chouteau 1998). Again this type of data is often used to produce maps (Pedersen et al 1990), but sometimes also inverted to produce models of the density distribution (Droujinine et al 2007). Being a derivative of scalar gravity data it provides higher lateral resolution but the sensitivity kernels decay more quickly with depth.…”

Geophysical Investigations of the Siljan Impact Structure — A Short Review

“…Such high q-ratios do not normally occur in other parts of the TIB granitoid basement (which typically have q-ratios of 0.3 or less, see Table 2 and 3). In the residual magnetic map in Pedersen et al (1990), several small-scale features, indicative of narrow sills or dykes, have a crater symmetric pattern. They have, however, been interpreted as dyke features without any relation to the impact.…”

“…10 km. A description of the aeromagnetic features is found in Pedersen et al (1990). The absence of north-facing negative contact anomalies (and their positive counterparts on the south side), indicates either an antiform shape of the source structure or the presence of a remanent magnetization that neutralizes the asymmetry related to the inclination of the geomagnetic field.…”

“…In connection with the Deep Gas Project, a preliminary gravity model of the Siljan structure was made by Dyrelius (1990). In this context, the erroneous assumption was made that the large gravity low in the northern part of the structure (Fig.…”

Obtaining vector magnetic field maps from single‐component measurements of geological samples

“…With the advancement of computer technology and the development of fast Fourier transform (FFT) algorithms, Lourenco and Morrison [1973] proposed in the early 1970s a method in the Fourier domain to transform a map of the total field anomaly into maps of the three Cartesian components. Later, a number of groups provided derivations of Fourier relations among derivatives of both magnetic [ Pedersen , 1989; Pedersen et al , 1990] and gravity [ Hinojosa and Mickus , 2002; Mickus and Hinojosa , 2001; Nelson , 1986, 1988] potential fields. The drawback of all of these Fourier methods is that they require knowledge of the magnetic field at all points on a surface and impose strong conditions on magnetic field spatial distribution, such as assuming the anomaly field is zero at the boundaries of the map.…”